Cad/cam device for electric discharge machine

ABSTRACT

A CAD/CAM device for an electric discharge machine comprises a check unit ( 32 ) for checking whether or not a level (H C ) of a clamp is lower than a safe level (H LS ) of the machining solution surface before conducting actual machining. The machining tank ( 7 ) can be automatically driven so that machining solution surface level H L  is set at safe level (H LS ). Therefore, before the process of actual machining, it is possible to check whether or not the clamp device ( 5 ) is soaked in the machining solution ( 8 ) when machining is actually conducted.

TECHNICAL FIELD

The present invention relates to improvements in a CAD/CAM device usedfor an electric discharge machine that conducts electric dischargemachining on a workpiece by supplying electric power for machining tobetween an electrode and the workpiece.

BACKGROUND ART

FIG. 4 is an arrangement view of an electric discharge machine. In theview, reference numeral 1 is a mechanical body of the electric dischargemachine, reference numeral 2 is a control section of the electricdischarge machine, reference numeral 3 is a motor of Z-axis, referencenumeral 4 is a head, reference numeral 5 is a clamp device, referencenumeral 6 is a surface plate, reference numeral 7 is a machining tank,reference numeral 8 is an insulating machining solution stored in themachining tank 7, reference numeral 9 is a motor for driving themachining tank, reference numeral 10 is a manual switch for elevatingthe machining tank, reference numeral 11 is an automatic electrodereplacing device, reference numeral 12 is a machining electric powersupply means, reference numeral 13 is a memory for storing an NCprogram, reference numeral 14 is an NC program analysis section,reference numeral 15 is a shaft drive section, reference numeral 16 is amachining tank drive section, reference mark E is an electrode,reference mark W is a workpiece, and reference mark H_(L) is a level ofa surface of the machining solution.

The shaft drive section 15, the motor 3 of Z-axis and motors of X-axisand Y-axis, which are not shown in the view, correspond to a positioningmeans. The machining tank drive section 16 and the machining tank drivemotor 9 correspond to a machining tank drive means for changing levelH_(L) of the surface of the machining solution with respect to workpieceW when the machining tank 7 is driven and made to ascend and descend.

Electrode E can be attached to and detached from the clamp device 5 ofthe head 4 by the automatic electrode replacing device 11. Electrode Eis attached to the clamp device 5 of the head 4, and workpiece W is putand fixed onto the surface plate 6 arranged in the machining tank 7.Under the above condition, electrode E and workpiece W are relativelypositioned by the positioning means, and then electric discharge isgenerated in the machining solution 8 while voltage is being impressedupon between electrode E and workpiece W by the machining electric powersupply means 12. When electric discharge is generated between electrodeE and workpiece W, workpiece W is melted and removed, so that electricdischarge machining can be carried out.

An NC program for giving a command of operation of the electricdischarge machine is stored in the memory 13. This NC program isanalyzed by the NC program analysis section 14. This NC program analysissection 14 outputs moving commands to the shaft drive section 15 and themachining tank drive section 16.

An ascending and descending motion of the machining tank 7 is carriedout by the machining tank drive motor 9 that is driven by the machiningtank drive section 16. When the machining tank 7 is made to ascend anddescend by the machining tank drive motor 9, level H_(L) of the surfaceof the machining solution is changed with respect to the position ofworkpiece W. For example, as disclosed in JP-A-5-261620, level H_(L) ofthe surface of the machining solution is set at a position higher thanthe level of workpiece W by a distance not less than 50 mm, for example,level H_(L) of the surface of the machining solution is set at aposition higher than the level of workpiece W by a safe distance ofabout 100 mm. The reason why level H_(L) of the surface of the machiningsolution is set at the position described above will be explained asfollows. When level H_(L) of the surface of the machining solution istoo low with respect to the level of workpiece W, electric discharge isconducted in air. Accordingly, there is a possibility of the occurrenceof fire. When level H_(L) of the surface of the machining solution istoo high with respect to the level of workpiece W, it is difficult foran operator to observe a state of electric discharge. Further, the clampdevice 5 is soaked in the machining solution 8, which could cause amechanical breakdown.

When machining solution surface level H_(L) is set at a level which isobtained when a safe distance is added to the level of workpiece W (Thislevel is referred to as “safe level” H_(LS) hereinafter.), it isnecessary for an operator to adjust the level of the machining tank 7 bythe manual switch 10 for ascending and descending the machining tank oralternatively it is necessary for an operator to give a command of thesafe level or safe distance by an NC program. Each time the level ofworkpiece W is changed, safe level H_(LS) must be adjusted, and furtherthe operator must always conduct the adjustment.

FIG. 5 is a system arrangement view of the conventional CAD/CAM device17. In the view, reference numeral 18 is an electrode drawing data,reference numeral 19 is a workpiece drawing data, reference numeral 20is a path deciding section, reference numeral 21 is an NC program,reference numeral 22 is a path checking means, and reference numeral 23is a display means such as a CRT.

In the conventional CAD/CAM device 17, the electrode drawing data 18 andthe workpiece drawing data 19 are read in, and the path deciding section20 decides a path of the machining motion according to the data whichhave been read in and the NC program 21 is created. The thus created NCprogram 21 is stored in the memory 13 arranged in the control section 2of the electric discharge machine shown in FIG. 4. The path check means22 confirms a path between electrode E and workpiece W.

As the method of checking the NC program 21, there are provided twomethods. One is a method of graphic check conducted on a display of thedisplay means 23, and the other is a method of dry-run check conductedby a dry running. The method of graphic check is conducted as follows.In the graphic check, the machine is not actually operated but the NCprogram 21 is operated on the display means 23 or the display of theelectric discharge machine so as to conduct checking on each shaft. Thepath is graphically displayed on the display means 23 or the display ofthe electric discharge machine, so that operation of each shaft can bechecked by the coordinate values shown on the display. In the method ofdry-run check, operation of each shaft is checked while the machine isbeing operated. Dry running in which the workpiece is not actuallymachined is conducted while the machining solution 8 is not beingprovided, so that operation of each shaft can be checked at high speed.

Setting of level H_(L) of the machining solution at safe level H_(LS)depends upon the operator as described above. Therefore, it isimpossible for the conventional methods of graphic check and dry-runcheck to check a positional relation between electrode E and levelH_(LS) of the surface of the machining solution. Accordingly, even ifgraphic check and dry-run check are conducted, the following problemsmay be encountered. When electrode E to be used is too short, the clampdevice 5 is soaked in the machining solution 8 in the process ofelectric discharge machining. Alternatively, when machining is conductedat a deep position in the machining solution, the clamp device 5 issoaked in the machining solution 8.

When it is found that electrode E cannot be used as described abovebecause the clamp device 5 has been soaked in the machining solution 8after the actual machining process, electrode E must be manufacturedagain, which causes a decrease in the productivity and an increase inthe manufacturing cost.

Especially in the case where a profile of workpiece W is complicated ora plurality of workpieces W, the level of which are different from eachother, are present, and further in the case where machining is conductedwhile a plurality of electrodes E are being replaced by the automaticelectrode replacing device 11, from the viewpoint of accomplishingautomation, it is very important that safe level H_(LS) necessary foractual machining operation is recognized and the machining tank 7 isautomatically driven so that level H_(L) of the surface of the machiningsolution can be set at safe level H_(LS). Furthermore, in the case wherethe profile of workpiece W is complicated, it is necessary to preciselycheck the length of electrode E before actual machining operation isstarted.

DISCLOSURE OF THE INVENTION

The present invention has been accomplished to solve the above problems.It is an object of the present invention to provide a CAD/CAM deviceused for an electric discharge machine characterized in that: a safelevel of an electrode can be recognized in an actual machining processand a machining tank is automatically driven so that a level of asurface of the machining solution can be set at the safe level; and evenif a profile of a workpiece is complicated, it is possible to checkwhether or not a clamp device is soaked in the machining solution whenactual machining is conducted.

The present invention provides a CAD/CAM device for an electricdischarge machine comprising: a machining tank for storing a machiningsolution; a positioning device for relatively moving a workpiece, whichis fixed to a surface plate arranged in the machining tank, and anelectrode; a machining electric power supply means for supplyingmachining electric power to between the workpiece and the electrode; anda machining tank drive means for changing a level of a surface of themachining solution with respect to the workpiece by driving themachining tank, the CAD/CAM device for an electric discharge machinefurther comprising a check means for checking whether or not a level ofa predetermined position of a device to be protected from being soakedin the machining solution is lower than a safe level of a surface of themachining solution when a safe level of the surface of the machiningsolution, which is obtained when a predetermined safe distance is addedto a level of a predetermined position of the workpiece with respect toa predetermined reference position, is compared with the level of thepredetermined position of the device with respect to the predeterminedreference position before conducting actual machining.

The present invention provides a CAD/CAM device for an electricdischarge machine comprising: a machining tank for storing a machiningsolution; a positioning device for relatively moving a workpiece, whichis fixed to a surface plate arranged in the machining tank, and anelectrode; a machining electric power supply means for supplyingmachining electric power to between the workpiece and the electrode; anda machining tank drive means for changing a level of a surface of themachining solution with respect to the workpiece by driving themachining tank, the CAD/CAM device for an electric discharge machinefurther comprising a check means for checking whether or not a level ofa clamp is lower than a safe level of the machining solution when a safelevel of the surface of the machining solution, which is obtained when apredetermined safe distance is added to a level of a predeterminedposition of the workpiece with respect to a predetermined referenceposition, is compared with a level of a clamp which is obtained when alength of the electrode is added to a level of a machining finishingposition of the workpiece with respect to the predetermined referenceposition before conducting actual machining.

The present invention provides a CAD/CAM device for an electricdischarge machine comprising: a machining tank for storing a machiningsolution; a positioning device for relatively moving a workpiece, whichis fixed to a surface plate arranged in the machining tank, and anelectrode; a machining electric power supply means for supplyingmachining electric power to between the workpiece and the electrode; anda machining tank drive means for changing a level of a surface of themachining solution with respect to the workpiece by driving themachining tank, the CAD/CAM device for an electric discharge machinefurther comprising a check means for checking whether or not a level ofa clamp is lower than a safe level of the machining solution when a safelevel of a surface of the machining solution, which is obtained when apredetermined safe distance is added to a level of a predeterminedposition of the workpiece with respect to a predetermined referenceposition on the basis of workpiece drawing data, is found and when asafe level of the surface of the machining solution is compared with alevel of a clamp which is found when a length of the electrode is addedto a level of a machining finishing position of the workpiece withrespect to the predetermined reference position on the basis ofelectrode drawing data before conducting actual machining.

The present invention provides a CAD/CAM device for an electricdischarge machine comprising: a machining tank for storing a machiningsolution; a positioning device for relatively moving a workpiece, whichis fixed to a surface plate arranged in the machining tank, and anelectrode; a machining electric power supply means for supplyingmachining electric power to between the workpiece and the electrode; anda machining tank drive means for changing a level of a surface of themachining solution with respect to the workpiece by driving themachining tank, the CAD/CAM device for an electric discharge machinefurther comprising a machining tank level deciding means for deciding alevel of the machining tank so that a level of a surface of themachining solution can be a level obtained when a predetermined safelevel is added to a level of a predetermined position of the workpiecewhich is found on the basis of workpiece drawing data, wherein an NCprogram to drive the machining tank drive means is outputted so that thelevel of the machining tank can be a value found by the machining tanklevel deciding means.

The CAD/CAM device for an electric discharge machine of the presentinvention is composed as described above. Therefore, it is possible forthe device to recognize a safe level of a surface of a machiningsolution which is necessary when machining is actually conducted, and itis also possible for the device to automatically drive a machining tankso that a level of the machining solution in the machining tank can beset at the safe level. It is also possible for the device to checkbefore machining is actually conducted whether or not a clamp device issoaked in the machining solution in the process of actual machining.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an arrangement view showing a CAD/CAM device for an electricdischarge machine of an embodiment of the present invention.

FIGS. 2(a) and 2(b) are schematic illustrations showing an example ofelectrode drawing data and also showing an example of workpiece drawingdata.

FIG. 3 is a flow chart showing a method of checking whether or not clamplevel H_(C) can be maintained at safe level H_(LS).

FIG. 4 is an arrangement view showing an electric discharge machine.

FIG. 5 is an arrangement view showing a conventional CAD/CAM device foran electric discharge machine.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is an arrangement view showing a CAD/CAM device 24 for anelectric discharge machine of an embodiment of the present invention. Inthe drawing, reference numeral 18 is electrode drawing data, referencenumeral 19 is workpiece drawing data, reference numeral 20 is a pathdeciding section, reference numeral 21 is an NC program, referencenumeral 22 is a path check means, reference numeral 23 is a displaymeans such as a CRT, reference numeral 25 is a machine parameter,reference numeral 26 is a machining tank parameter, reference numeral 27is an electrode length analysis section, reference numeral 28 is aworkpiece level analysis section, reference numeral 29 is a workpieceactual machining level deciding section, reference numeral 30 is anelectrode replacing time machining tank level deciding means, referencenumeral 31 is a machining tank level deciding means, and referencenumeral 32 is a check means for checking a length of an electrode. Likereference characters are used to indicate like parts in FIG. 1 and FIG.5 in which the conventional CAD/CAM device 17 is shown.

An arrangement of the electric discharge machine, in which the CAD/CAMdevice 24 for an electric discharge machine of the embodiment of thepresent invention is used, is the same as that shown in FIG. 4 explainedin the prior art before. Therefore, explanations of the electricdischarge machine will be omitted here.

FIG. 2 is a schematic illustration showing an example of electrodedrawing data 18 and also showing an example of workpiece drawing data19. Electrode drawing data 18 shown in FIG. 2(a) has pieces ofinformation such as the length L of electrode E. Reference numeral 18 ais a body of electrode E, reference numeral 18 b is a shank, andreference numeral 18 c is a shank cross pin. Workpiece drawing data 19shown in FIG. 2(b) has pieces of information such as the profile andlevel of workpiece W. A hatched portion of workpiece drawing data 19shows a machining region.

In FIG. 1, the machine parameter 25 has pieces of information such asthe level of the surface plate 6 and the safe distance, and themachining tank parameter 26 has pieces of information such as the levelposition of the machining tank 7. The workpiece level analysis section28 finds a level of workpiece W from workpiece drawing data 19. In thiscase, it is possible to find a level of each workpiece W. It is alsopossible to find the maximum level of workpiece W for each workpiece Win the machining conducted once. Concerning the thus found level ofworkpiece W, a machine parameter in the direction of a level (directionof Z-axis), to which consideration should be given when machining isactually conducted, such as a level of the surface plate 6 is consideredin the workpiece actual machining level deciding section 29, so that alevel of actual machining of workpiece W with respect to a predeterminedreference position can be decided.

FIG. 3 is a flow chart showing a method of checking before conductingactual machining whether or not a level of a position (this level isreferred to as “clamp level” H_(C) hereinafter), at which length L ofelectrode E is added to a level of a position at which machining ofworkpiece W is completed, can maintain safe level H_(LS), that is, alevel obtained when a safe distance is added to a level of an upper faceof workpiece W. Steps from S1 to S5 will be explained as follows.

S1: Read in workpiece drawing data 19.

In this step, workpiece drawing data 19 is read into the workpiece levelanalysis section 28.

S2: Calculate safe level H_(LS).

In this step, a level of workpiece W is found by the workpiece levelanalysis section 28. On the basis of a level of workpiece W and also onthe basis of information relating to a level of workpiece W such as alevel of the surface plate 6 of the machine parameter 25, a level of anupper face of workpiece W with respect to a predetermined referenceposition of workpiece W is found by the workpiece actual machining leveldeciding section 29.

Next, safe level H_(LS) is found by the check means 32 from pieces ofinformation of the level of an upper face of workpiece W and the safedistance of the machine parameter 25.

S3: Read in electrode drawing data 18.

Electrode drawing data 18 is read into the electrode length analysissection 27.

S4: Calculate clamp level H_(C).

A level of workpiece W is found by the workpiece level analysis section28. On the basis of this level of workpiece W and also on the basis ofinformation relating to a level of workpiece W such as a level of thesurface plate 6 of the machine parameter 25, a level of actual machiningwith respect to a predetermined reference position of workpiece W isfound by the workpiece actual machining level deciding section 29. Aposition of completion of machining (position in the level direction) isfound by the check means 32 according to the NC program 21.

Next, clamp level H_(C) is found by the check means 32 from length L ofelectrode E, which is found by the electrode length analysis section 27,and the machining completion position (position in the level direction).

S5: Judge whether or not the clamp device 5 is soaked in the machiningsolution 8.

Whether or not the clamp device 5 is soaked in the machining solution isjudged from safe level H_(LS), which is found in step S2, and clamplevel H_(C), which is found in step S4, by the check means 32 asfollows.

In the case of H_(C)>H_(LS), the clamp device 5 is not soaked in themachining solution 8. Therefore, it is judged to be normal. In the caseof H_(C)≦H_(LS), the clamp device 5 is soaked in the machining solution8. Therefore, it is judged to be abnormal. Therefore, an error signal isoutputted on the display means 23 so as to warn an operator.

As described above, it is possible to check by the check means 32 beforeconducting actual machining whether or not the clamp device 5 is soakedin the machining solution 8.

In step S2 described before, a level of the upper face of workpiece Wwith respect to the predetermined reference position of workpiece W isfound by the workpiece actual machining level deciding section 29. Bythe machining tank level deciding means 31, safe level H_(LS) is foundfrom a level of the upper face of workpiece W, which is sent from theworkpiece actual machining level deciding section 29, and also frominformation of the safe distance of the machine parameter 25. Further,from information of the machining tank parameter 26, it is possible tofind a position of the machining tank 7 at which machining solutionlevel H_(L) becomes safe level H_(LS).

Accordingly, it is possible to output an NC code, by which the machiningtank 7 is moved so that machining solution surface H_(L) can become safelevel H_(LS), from the machining tank level deciding means 31 to the NCprogram 21. Due to the foregoing, a position of the machining tank 7 torealize safe level H_(LS) is outputted into the memory 13 of the controlsection 2 of the electric discharge machine shown in FIG. 4 as the NCprogram 21. When the NC program 21 stored in the memory 13 is analyzedby the NC program analysis section 14 and a movement command is sent tothe machining tank drive section 16, the machining tank 7 can be movedto a position at which machining solution surface level H_(L) can becomesafe level H_(LS).

Since the NC program 21 to give a movement command to the machining tankdrive section 16 is made as described above, it is possible toautomatically set machining solution surface level H_(L) at safe levelH_(LS) in the process of actual machining. Therefore, a burden imposedon an operator can be greatly reduced.

In the case where electrode E is replaced by the automatic electrodereplacing means 11 shown in FIG. 4, a position of the machining tank 7is decided by the electrode replacing time machining tank level decidingmeans 30 so that electrode E and the machining tank 7 can not interferewith each other, and an NC code by which the machining tank 7 is movedto this position may be outputted to the NC program 21.

In the case where a plurality of workpieces, the levels of which aredifferent from each other, are provided, the position of the machiningtank 7 may be controlled on the basis of a workpiece, the level of whichis the largest. Alternatively, the position of the machining tank 7 maybe controlled for each workpiece to be machined.

The above explanations are made into a case in which machining solutionsurface level H_(L) is set at safe level H_(LS) which is obtained when asafe distance is added to a level of the upper face of workpiece W.However, for example, in the case where a profile of workpiece W iscomplicated and machining is not started from an upper face of workpieceW, machining solution surface level H_(L) may be set at a level which isobtained when a safe distance is added to a level of the machining startpoint of workpiece W, that is, safe level H_(LS) may be set at a levelobtained when a safe distance is added to a level of a predeterminedposition in workpiece W.

The above explanations are made into a case in which safe level H_(LS)and clamp level H_(C) are compared with each other for judgment so thatthe clamp device 5 can not be soaked in the machining solution 8.However, the present invention is not limited to the above case, thatis, depending upon the constitution of an electric discharge machine,not clamp level H_(C) but a level of another device to be protected fromsoaking in the machining solution 8 may be used.

Industrial Applicability

As described above, the CAD/CAM device used for an electric dischargemachine of the present invention is suitably used for machining aworkpiece by supplying electric power for machining to between anelectrode and the workpiece. Especially, the CAD/CAM device used for anelectric discharge machine of the present invention is suitably used forautomatizing an electric discharge machining work.

What is claimed is:
 1. A CAD/CAM device for an electric dischargemachine comprising: a machining tank for storing a machining solution; apositioning device for relatively moving a workpiece, which is fixed toa surface plate arranged in the machining tank, and an electrode; amachining electric power supply means for supplying machining electricpower to between the workpiece and the electrode; and a machining tankdrive means for changing a level of a surface of the machining solutionwith respect to the workpiece by driving the machining tank, the CAD/CAMdevice for an electric discharge machine further comprising a checkmeans for checking whether or not a level of a predetermined position ofa device to be protected from being soaked in the machining solution islower than a safe level of a surface of the machining solution when asafe level of the surface of the machining solution, which is obtainedwhen a predetermined safe distance is added to a level of apredetermined position of the workpiece with respect to a predeterminedreference position, is compared with the level of the predeterminedposition of the device with respect to the predetermined referenceposition before conducting actual machining.
 2. A CAD/CAM device for anelectric discharge machine comprising: a machining tank for storing amachining solution; a positioning device for relatively moving aworkpiece, which is fixed to a surface plate arranged in the machiningtank, and an electrode; a machining electric power supply means forsupplying machining electric power to between the workpiece and theelectrode; and a machining tank drive means for changing a level of asurface of the machining solution with respect to the workpiece bydriving the machining tank, the CAD/CAM device for an electric dischargemachine further comprising a check means for checking whether or not alevel of a clamp is lower than a safe level of the machining solutionwhen a safe level of the surface of the machining solution, which isobtained when a predetermined safe distance is added to a level of apredetermined position of the workpiece with respect to a predeterminedreference position, is compared with a level of a clamp which isobtained when a length of the electrode is added to a level of amachining finishing position of the workpiece with respect to thepredetermined reference position before conducting actual machining. 3.A CAD/CAM device for an electric discharge machine comprising: amachining tank for storing a machining solution; a positioning devicefor relatively moving a workpiece, which is fixed to a surface platearranged in the machining tank, and an electrode; a machining electricpower supply means for supplying machining electric power to between theworkpiece and the electrode; and a machining tank drive means forchanging a level of a surface of the machining solution with respect tothe workpiece by driving the machining tank, the CAD/CAM device for anelectric discharge machine further comprising a check means for checkingwhether or not a level of a clamp is lower than a safe level of themachining solution when a safe level of a surface of the machiningsolution, which is obtained when a predetermined safe distance is addedto a level of a predetermined position of the workpiece with respect toa predetermined reference position on the basis of drawing data of theworkpiece, is found and when a safe level of the surface of themachining solution is compared with a level of a clamp which is foundwhen a length of the electrode is added to a level of a machiningfinishing position of the workpiece with respect to the predeterminedreference position on the basis of drawing data of the electrode beforeconducting actual machining.
 4. A CAD/CAM device for an electricdischarge machine comprising: a machining tank for storing a machiningsolution; a positioning device for relatively moving a workpiece, whichis fixed to a surface plate arranged in the machining tank, and anelectrode; a machining electric power supply means for supplyingmachining electric power to between the workpiece and the electrode; anda machining tank drive means for changing a level of a surface of themachining solution with respect to the workpiece by driving themachining tank, the CAD/CAM device for an electric discharge machinefurther comprising a machining tank level deciding means for deciding alevel of the machining tank so that a level of a surface of themachining solution can be a level obtained when a predetermined safelevel is added to a level of a predetermined position of the workpiecewhich is found on the basis of drawing data of the workpiece, wherein anNC program to drive the machining tank drive means is outputted so thatthe level of the machining tank can be a value found by the machiningtank level deciding means.